CM 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 12 13 14 15 16 17 18 19 Common Arthropods of the Inter0dal Zone This visual guide is intended to aid you in iden1fying crabs and shrimp commonly captured while seining on the beaches of Long Island. This guide does not list all possible species. Always take photographs of all captures, and use a comprehensive field guide when any species iden1fica1on is debatable. www.portaltodiscovery.org/aday inches 0 9 8 7 6 5 4 3 2 1
Blue Crab. Two sharp pincers, elongated carapace with long spines on the long ends. Nine points from eye to edge of carapace, including long spines. Last pair of legs flaGened into swimmerets. Dangerous to handle. Up to 22cm. Figure 1a. Blue Crab (adult) Callinectes sapidus Figure 1b. Blue Crab (juvenile) Callinectes sapidus Lady Crab. Two sharp pincers, pentagonal mogled carapace. Five points from eye to edge of carapace. Last pair of legs flaGened into swimmerets. Up to 7cm. Commonly called 'calico crab'. Figure 2. Lady Crab (juvenile) Ovalipes ocellatus Green Crab. Broad pincers, 4 pairs of walking legs. Carapace olive green, underside pale green or orange. Five points from eye to edge of carapace. Up to 7cm. Figure 3. Green Crab Carcinus maenas
Spider Crab. Long pincers, more robust on mature males than females. Knobby carapace. OUen festooned with algae, especially juveniles. Carapace up to 10cm, leg span up to 30cm. Figure 4a. Spider Crab (male) Libinia spp. Figure 4b. Spider Crab (female) Libinia spp. Figure 4c. Spider Crab (juvenile) Libinia spp. showing algae decoravons Asian Shore Crab. This invasive species is found under rocks in the intervdal zone. Square carapace, mogled or pagered; color varies widely. Overall quite flat. Three spines from eye to edge of carapace. Up to 4cm. Figure 5. Asian Shore Crab Hemigrapsus sanguineus Rock Crab. Broad, oval carapace, reddish coloravon. Nine small spines from eye to edge of carapace. Up to 13cm. Figure 6. Rock Crab Cancer irroratus
Mud Crab. Several similar species. Small, dark colored crab. Carapace twice as wide as long. Claws unequal. Has black or chocolate 'fingervps'. Up to 4cm. Figure 7. Mud Crab Panopeus spp. Long-clawed Hermit Crab. Small hermit crab, associated with periwinkle, mud snail or oyster drill shells. One pincer larger than the other and cylindrically shaped. Only two pairs of walking legs. Carapace less than 1cm long. Figure 8. Long-clawed Hermit Crab Pagurus longicarpus Flat-clawed Hermit Crab. Large, associated with moon snail or whelk shells. Dominant claw flat and broad, covered in tubercles. Pinkish to orange color. Carapace up to 3cm, dominant claw larger. Figure 9. Flat-clawed Hermit Crab Pagurus pollicaris Mole Crab. Egg-shaped and sand-colored. Live beneath the sand of the intervdal zone on highenergy beaches, emerging to feed in the surf. Excellent swimmers and awesome burrowers. Females to 2.5cm, males half that. Figure 12. Mole Crab Emerita talpoida
Fiddler Crab. Found on sandy or muddy beach areas in salt marshes, rarely in the water. Dig protecvve burrows in colonies. Males have one large claw longer than body length, females have more sensibly sized claws. Carapace 2cm to 3cm wide. Figure 10a. Fiddler Crab (female) Uca spp. Figure 10b. Fiddler Crab (male) Uca spp. Figure 10c. Fiddler Crab Colony Horseshoe Crab. You can't confuse this with any other animal. Body in three segments. Females large, up to 30cm long, males somewhat smaller. Males first pair of pincers rounded, like boxing gloves. Juveniles are sand colored. Figure 11c. Horseshoe Crab (female) Limulus polyphemus Figure 11b. Horseshoe Crab (male) Limulus polyphemus Figure 11a. Horseshoe Crab Limulus polyphemus
Sand Shrimp. Short rostrum (nose spike), long antennae. Dorsally compressed, ouen speckled like sand. Up to 7cm. Figure 13. Sand Shrimp Crangon septemspinosa Figure 14. Grass Shrimp Papaemonetes spp. Grass Shrimp. Serrated rostrum (nose spike), long antennae. Translucent body. Tends to stay near structure; docks, rocks, seaweed. To 5cm. Also called 'shore shrimp'. Man0s Shrimp. Somewhat shrimp-like, flagened profile. Three pairs of walking legs, three pairs of feeding legs, and a large pair of predatory claws. Dangerous to handle. Up to 25cm. Uncommon. Figure 15. Man0s Shrimp Squilla empusa Lobster. Massive arthropod. Ten legs, the front three pairs have claws. The front pincers are assymetrical. One has knobby bumps inside for crushing, the other more serrated for ripping. Dangerous to handle. Up to 64cm. Figure 16. Lobster Homarus americanus